Speaking strictly of my experience with ME2, as mingus said, streamlined would be a good word for it. The character building process is limited to picking a class from a list of maybe five or six(?) which correspond to various styles of play (tank, sniper, stealth, etc) that will determine which skills and weapons you're able to use from the start. Physical stats like health, speed, and those kind of things are also determined by this. They'll increase as you level up but the class choice matters towards which will be emphasized more. You don't get to put points towards making your character faster or more accurate specifically, rather one of the four skills available to put your build points into is usually some sort percentage increase to your health and damage while the other three are active combat skills which can be upgraded as well. With the exception of a couple of specialized weapons you can get late in the game weapon improvements are made across the board for classes of weapons. So if you find a new assault rifle all of your party members that can use rifles can select if from their weapon loadout at the start of the mission. If your improve your pistol's accuracy everyone's pistol gets more accuratte. There's no inventory to speak of except for the healing items, each character can carry only one of whatever kind of weapons they can use (which are fixed. One character might only be able to use pistols and shotguns, while another uses a sniper rifle and SMG.) YMMV depending on your love of minutiae. Some people find the system limiting, others figure they would have to specialize their team along those lines anyways. Not all skills are created equal, but the system makes it hard to up any character ireparably. Later in the I think you even get the option to reassign skill points for a price.
Likewise there's not much of a free roaming aspect to it, no sandbox sort of experience. The game's very clear in where you need to go next to keep the story moving, occasionally even forcing your hand on a few plot central missions. During the missions it pays to search every nook and cranny for upgrades and side missions but for the most part they are fairly linear and impossible to get lost on. You can dig through every system in the galaxy (and the mining stuff gets tiresome pretty quick) to find a few hidden missions here and there but for the most part the whole thing progresses in a straight forward fashion.
The dialogue stuff can be a little frustrating. In almost every conversation you'll have paragon (nice guy) and renegade (tough guy) responses as well as various instances where you can interupt certain conversations with similar choices. The most natural way to go for most players would be a blend of the two because your team and all the people that you run across cover a wide array of personalities. You'll likely be sympathetic to some and want to tell others to off. But from a practical standpoint it makes more sense to lean on one side of the other the whole way through because at certain points having a high enough ranking in either opens up an extra option in some key moments.